In underground mining applications, conveying systems are used to transport, for example, extracted minerals such as coal or stone. Usually, a face conveyer is configured to be disposed under shield supports arranged within a longwall face. The face conveyer transports the coal extracted from the longwall face by a plow into a drift, where a gate conveyer is disposed for transporting the extracted minerals out of the underground mine. The face conveyer is equipped with a chain reciprocally running on an upper run and lower run, carrier elements connected to the chain for taking the minerals along the conveyor, a sprocket disposed at least at one end of the face conveyor for driving the chain, and at least one main driving device configured to drive the sprocket. The chain is configured to be wound around the sprocket.
Prior operation of the conveyor, the chain needs to be brought in place and tensioned, which means that both ends of the chain needs to be brought together for forming a closed chain running in the upper and lower runs of the conveyor. For achieving this, in prior art systems, a chain tensioning apparatus externally attached to the main driving device is configured to input torque to the sprocket for bringing the ends of the chain together, as the output torque of the main driving unit, which drives the chain during normal operation of the conveyor, may be inappropriate for performing the installation process of the chain.
During operation, the chain may be tensioned or loosened by axially displacing at least one of the sprockets disposed at each end of the conveyor. However, in cases that axial displacement of the at least one sprocket may not be sufficient to tension the chain, the above-mentioned chain tensioning apparatus may be used for tensioning the chain. Thus, the chain tensioning apparatus tensions the chain when either the chain may be installed in the face conveyor or when the axial displacement of the at least one sprocket may be not sufficient to tension the chain.
U.S. Pat. No. 5,171,065 A discloses a mineral mining installation with chain-tensioning systems, wherein a plow box containing a chain wheel driving a chain to propel a chain used to move a plow is mounted for displacement alongside a machine frame at one end of a scraper chain conveyer.
CN 201 089 632 Y discloses a worm-gear self-locking conveying-belt loosening and tightening machine.
GB 1 198 024 A relates to a tensioning system configured to axial displace a tensioning role over which the chain of the face conveyer runs. By axially displacing the tensioning role, the chain may be tensioned or loosened.
The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems.